258 NATURAL SCIENCE. April, 



season [Astacopsis, Telphusa). (2) Those which require that their eggs 

 shall be dried up prior to development [Apus, Estheria, Liinnadopsis, 

 Limiteiis, Eiilimnadia)." The rate of growth of Apus and Estheria 

 seems to be extraordinary : specimens of the former measuring 2h to 

 3 inches were found, and there was reason to believe that these had 

 developed from the eggs in a few days. Such capabilities are of 

 obvious utility in a region subject to frequent and prolonged droughts. 



Of Insects lists are-given of several orders, but there is evidently 

 much more work to be done in this department. Of special interest 

 are the Australian honey-ants, of which Mr. Froggatt gives a particular 

 account. These belong to the genus Canipamtus, of which more than 

 thirty species are known from Australia, yet only three of these have 

 developed the honey-storing habit. The peculiarity consists in this, 

 that certain individuals are set apart as receptacles and fed with 

 honey by their fellows till their abdomen is hugely distended, and in 

 subsequent periods of scarcity made to disgorge their precious burden. 



Finally, we must mention the description of a stridulating organ 

 in Phlogius by Prof. Spencer, similar to those which have already been 

 discussed by Mr. Pocock (Natural Science, vol. vi., p. 44). 



Geology. 



The Physical Geography, Geology, and Palaeontology are dealt 

 with by Prof. Ralph Tate, Mr. Watt, and Mr. Smeeth. As already 

 mentioned, it would appear from their observations that the high 

 ground of the McDonnell and other ranges is formed by Precambrian 

 and Ordovician rocks, while the foot-hills consist of Cretaceous strata. 

 The great plains are of post-Cretaceous age, and covered by a series 

 of deposits regarded as intermediate between the Cretaceous and 

 Eocene, and named Paleocene. Most of the valleys result from the 

 erosion of Ordovician limestones by the rivers. The two lakes met 

 with are rapidly drying up, and the largest. Lake Eyre, with an area 

 of 5,000 square miles, is calculated to be 39 feet below the sea-level. 



The determination of the great series of highly altered rocks as 

 Precambrian is based upon their general resemblance to undoubted 

 strata of this antiquity in other parts of Central and South Australia. 

 Regional metamorphism is extensive, and large areas are occupied 

 by eruptive rocks, of which several types {e.g., diorites and dolerites) 

 are described in a petrographical section of the Report. Foliation 

 planes are abundantly obvious, and have been previously mistaken for 

 planes of sedimentation ; but there is a remarkable absence of 

 contortions. 



The Ordovician rocks comprise ripple-marked and false-bedded 

 sandstone, quartzites, and limestones. No evidence of contem- 

 poraneous volcanic action was obtained by the expedition ; but many 

 typical fossils were found in the limestones. A post-Ordovician con- 

 glomerate was also noticed in some localities. 



The Desert Sandstone, of " Paleocene Age," is a remarkable 



